/// <summary>
/// 排列递归方法。
/// </summary>
/// <param name="array">元素数组。</param>
/// <param name="ii">已循环到的元素数组的索引。</param>
/// <param name="created">排列完成一组元素后的回调函数。</param>
/// <param name="userState">传递用户参数。</param>
private static void Permutate(IList <T> array, int ii, CreatedCallback created, object userState)
{
if (ii == array.Count - 1)
{
T[] result = new T[array.Count];
array.CopyTo(result, 0);
created?.Invoke(result, userState);
}
else
{
for (int i = ii; i < array.Count; i++)
{
if (i == ii)
{
Permutate(array, ii + 1, created, userState);
}
else
{
Swap(array, i, ii);
Permutate(array, ii + 1, created, userState);
Swap(array, i, ii);
}
}
}
}
/// <summary>
/// 组合递归方法。
/// </summary>
/// <param name="array">元素数组。</param>
/// <param name="m">指定选择的元素数量。</param>
/// <param name="ii">循环到的主要分段元素数组的索引。</param>
/// <param name="jj">循环到的盈余分段元素数组的索引。</param>
/// <param name="created">组合完成一组元素后的回调函数。</param>
/// <param name="userState">传递用户参数。</param>
private static void Combine(IList <T> array, int m, int ii, int jj, CreatedCallback created, object userState)
{
for (int i = ii; i < m; i++)
{
for (int j = jj; j < array.Count; j++)
{
Swap(array, i, j);
Combine(array, m, i + 1, j + 1, created, userState);
Swap(array, i, j);
}
}
T[] result = new T[m];
for (int i = 0; i < result.Length; i++)
{
result[i] = array[i];
}
created?.Invoke(result, userState);
}